movement planning in developmental coordination disorder

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Movement planning in Developmental Coordination Disorder. Kate Wilmut , Maia Byrne and Anna Barnett. Action Sequences. Actions are composed of a string of movements, each movement taking into account the next - PowerPoint PPT Presentation

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Planning movement by anticipating end-goal in children with Developmental Coordination Disorder

Kate Wilmut, Maia Byrne and Anna BarnettMovement planning in Developmental Coordination Disorder

1Action SequencesActions are composed of a string of movements, each movement taking into account the next

Internal forward modelling allows anticipation of motor consequences prior to execution (Wolpert & Kawato, 1998)

Allows a spatially and temporally optimal movement (Haggard, 1998; Rosenbaum, Vaughan, Barnes, & Jorgensen, 1992)

2Intended actionIntended action also effects initial kinematics of the reach-to-grasp when initial demands of a reach component are identical

In adultsElongated deceleration phase for a fit vs. a throw action (Marteniuk et al. 1987) Larger peak aperture and larger peak deceleration for a throwing/placing action vs. a lift action (Armbruster & Spijkers, 2006)

In children10 month-old infants: higher peak velocity when reaching to throw vs. place (Claxton, Keen, & McCarty, 2003)4 years of age: elongated deceleration period when reaching to fit vs. reaching to throw (Chen & Yang, 2007).

3Intended action IN DCDDCD: explained by a deficit in the internal modelling of movement? (Maruff et al., 1999; Smits-Engelsman et al. 2007; Williams et al., 2006). Difficulty predicting the outcome of action

If so we would not expect these individuals to tailor a movement to an onward action.

Aim: To consider whether children and adults with DCD tailor a movement to the onward action 4ParticipantsAll reported current motor difficulties and none indicated any neurological deficit or comorbid condition that would explain their motor difficulties

AdultsChildrenTDDCDTDDCDN18182424Mean age24:1125:009:019:01Gender ratio f:m7:117:114:204:20MABC-2 percentile All > 20th All < 5thAll > 20thAll < 5thBOT-2 percentileAll < 15thADCChildhood6.6All < 1023.3(all > 18)Adulthood17.2All < 40 47.6(7 > 62)5METHOD

Grasped a cylinder and:Tight place (hole x1)Loose hole (hole x2)LiftThrow

A Vicon 3D motion capture system was used to track the movement of the thumb, index finger, knuckle and wrist of the dominant hand.

6Results: Movement DurationDCD group showed a longer movement duration compared to the TD individuals.

TD developmental improvementDCD no difference

Effect of action type: TD group: Lift > tight place = loose placeDCD group: Lift > Throw

7Results: Proportion time in decelerationDCD group spent a longer proportion of MT deceleratingTD developmental improvement, DCD no difference

Effect of action type:Adults: TD: tight >loose=lift>throw DCD: tight=loose=lift>throw Children: TD: tight=loose=lift>throwDCD: no effect 8Effects of action typeTD adultsShortened proportion of time spent decelerating for a throw action as compared to a place or lift movement Discriminated between the tight and loose place actionTD ChildrenShortened proportion of movement time in deceleration when throwing as compared to the other three actionsNo discrimination between the place actionAdults with DCDSame pattern as the TD childrenChildren with DCDDifference in the movement duration, longer for a lift vs. a throw action. No other differences. 9Effects of action typeAdults and children with DCD are able to concatenate actions and account for the onward action.

DCD group able to use internal forward modelling, even if it is not as sophisticated as that seen in TD adults.

Does it ever reach a fully mature level? Is it driven by different underlying mechanism(s)?Control of action in DCD is actually different to the typically developing population rather than simply delayed. 10Movement outcomeTo some extent all of the groups tailored initial reach movement to the intended action

Does this result in a more functional movement?For place movements:How long spent adjusting prior to placing.

11Movement outcome

Calculated % change in proportion of movement time spent decelerating from a tight place to a loose place Compared to the average adjustment time across tight and loose place trials. 12Movement outcomeSignificant relationship for the TD adults, r=-0.532 p=0.023Pp who showed a greater discrimination in deceleration period from tight to loose place showed a shorter overall adjustment time

Not significant for the TD children, the adults with DCD or the children with DCD.

13Functionality of movementIf the children and adults with DCD are failing (even if only in some respects) to concatenate movement does this actually matter?

Seems to be a functionality to predicting onward actionTD adults: relationship between the degree to which they discriminated between the two place actions during the initial reach phase and the time spent adjusting14ConclusionsBoth adults and children with DCD seem able to use forward modelling of inverse models to anticipate movement and concatenate action.

Not as sophisticated as that seen in typically developing adults.

Underlying forward anticipation of action may be different, rather than simply delayed in DCD.

15Any questions?Thank-you for listening16

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